Iron Man 3 was the first, showing the aftermath of Tony Stark’s would-be sacrifice in The Avengers and the PTSD he got from it.
Now in Phase 4, projects like WandaVision, The Falcon and the Winter Soldier, Loki, and Moon Knight have taken the opportunity to examine the mindsets and mental health of their lead characters.
Mental health has become one of the biggest themes of Marvel’s Phase 4, though it’s certainly been tackled in MCU projects prior to 2021.
Avengers: Endgame also takes the time to check in on the mental health of many of the Blip survivors, most notably Thor.